The subject invention relates to an improved machine for edging and beveling the periphery of plastic lenses wherein a high speed, self-cooled cutter does not require a liquid cutter coolant, and wherein a bevel aligning means automatically positions the cutter beveling notch at the desired position on the periphery of the lens during the cutting process. In addition, the subject invention includes a hydraulic cylinder that regulates the pressure of the cutter against the plastic lens by dampening the movement of the carriage that carries the cutter. The subject invention also includes a pressurized air cylinder that moves the carriage and the cutter away from the lens upon completion of the edging and beveling process.
Lenses are edged and beveled from blanks for insertion into a wide variety of frame contours other than round, such as oval and octagonal. Glass lenses at one time were the only type used, but in recent years plastic lenses have increasingly come into use. In most of the prior art, a diamond cutter, which is used to contour glass lenses, is also used to shape the new plastic lenses. Because of the heat generated by the diamond grinding wheel during the cutting process, a fluid coolant has been required. Problems associated with liquid cooling, typically leakage, corrosion, contaminants in the coolant resulting in overheating, and the necessity to change the coolant every day, are all present.
Lenses are contoured according to lens patterns supplied by the manufacturer of the lenses. A lens pattern in fact acts as a cam that, in turn, acts against a follower that effects a cutting of the lens in accordance with the pattern cam. The manufacturer also directs lens sizes, and, in addition to the contour of the periphery, the size of the lens must be introduced into the lens producing process.
In general, two types of lenses are produced, prescription lenses and sunglass lenses. Sunglass lenses are usually flat, while prescription lenses have various lens curvatures and thicknesses depending on the magnification required and other prescription necessities. A bevel must be formed around the periphery of lenses that is adapted to fit into the groove present around the inner side of eyeglass frames. This bevel must be formed either at the center of the lens periphery or at a specified distance from the front or back of the lens. Prescription lenses, for example, are often thick, and the bevel must be formed toward the front of the lens for aesthetic purposes.
In the prior art, the operator generally sizes down the lens blank in two or three stages so as to ensure that the position of the crown of the bevel is positioned correctly. This is a time-consuming process, and not only calls for constant operator attention, but it calls for a skilled operator.
Lens cutting machines in the prior art includes a movable head portion that carries a lens to be contoured and a lens pattern and a movable carriage portion that carries a lens cutter. One type of design has the head with the lens movable laterally relative to the carriage for beveling alignment of the lens relative to the cutter, and the carriage movable perpendicularly to the lateral movement of the head, or floating, for cutting and contouring the lens in accordance with the pattern. Another type has a head capable of being floated relative to the carriage and the carriage movable laterally. Variations on these designs are known.
An example of prior art disclosing a special cutting process for plastic lenses can be found in U.S. Pat. No. 4,191,501 issued Mar. 4, 1980 to Sinklier et al. The Sinklier patent discloses a cutting machine particularly directed to cutting and edging plastic lenses. The Sinklier patent provides a lens cutter that makes a rough cut of the lens by cutting plastic away from the periphery of the lens blank in a single radial bite rather than grinding away the periphery. It is the design of the machine itself that directs the cutter toward a single deep bite rather than the design of the cutter. The patent to Sinklier also discloses a means for mounting the lens cutter for free longitudinal, or horizontal, movement so that in a subsequent step after the rough cut, the cutter can automatically follow the curvature of the lens during additional rotation in order to provide a finishing cut and bevel. This horizontal movement is free floating rather than guided.
Other prior art cutting machines are disclosed in U.S. Pat. No. 3,786,600 issued Jan. 22, 1974 to Bloxom; and U.S. Pat. No. 4,203,259, issued May 20, 1980 to Haddock. The cited patents disclose various types of lens and lens pattern contouring devices.
Accordingly, it is an object of the subject invention to provide a new and improved lens edging machine that eliminates the need for liquid cooling of the lens cutter.
It is a further object of the subject invention to provide a new and improved lens edging machine that provides a high speed cutter that is capable of edging lenses at a high rate of production.
It is a still further object of the subject invention to provide a new and improved lens edging machine wherein a bevel aligning means is provided for automatically aligning the crown of the bevel to a selected position around the periphery of the lens.
It is still another object of the subject invention to provide a hydraulic dampening means for regulating the movement of the cutter against the lens.
It is still another object of the subject invention to provide a pressurized air means for moving the cutter away from the periphery of the lens when the edging and beveling operation has been completed.